The role of the ground wire is as follows:
Protection of electrical appliances, static electricity in the process of discharge will produce a large number of charges, if the appliances do not have the appropriate barrier will cause damage to the appliances, the role of the ground wire is the electrical appliances and the ground between the wire, can effectively avoid electrical appliances are strong charge damage.
Lightning protection, before if the occurrence of a lightning situation poles and electrical equipment are easy to be damaged by lightning strikes, so now will be grounded wire, so you can prevent lightning, to avoid electrical appliances are damaged.
Protect the normal work of the machine, many of the electrical appliances are necessary to electricity to work, especially in the medical field, the role of the ground wire is to be able to avoid a sudden power outage will not be affected, you can run some of the small load of the potential.
Protection of human safety, if the human body electrocution occurs, the ground wire can lead the current to the ground, so that the current through the human body will be much smaller, so as to protect the human body's life safety.
I hope the above information is helpful to you, if you have other questions, welcome to tell me.